Although the T-rex had been sculpted and molded for the first movie--making the resculpting of the character unnecessary--some additional sculpture work was required to create a male version that would be distinguishable from the female. "Even though the male would have different coloring", explained effects supervisor Shane Mahan, "we were concerned that, under certain lighting conditions it would be very hard to tell the two rexes apart. So, on the computer, I started manipulating photographs of the original T-rex. I did a series of eight different head shapes, all of which were submitted to Steven for approval.

Spielberg approved a male T-rex head that had an added neck wattle, a more prominent brow bone, and a battle scarred face. "There is a lot of science now to support the idea that carnivores like the T-rexes would have been really scarred up," Mahan Said, "with broken arms and legs and teeth knocked out. It makes sense, because they would have been battling each other for food all the time. In this film, the animals were in a more natural, wild , environment, rather than the safe containment of the man-made park, and that wpuld mean scarred bodies. Between the battle scars, the extended brow line, and the neck wattle, the male was a really distinctive animal." ... (Duncan, The Making of The Lost World: Jurassic Park)

....

...Shane Mahan produced eight male head designs by digitally manipulating photographic images of the original T-rex, then translated the approved concept into three dimensions, sculpting scars, neck wattle, and a pronounced brow ridge directly onto a replica of the original head of the original head for molding and the running of the new skins. John Rosengrant designed the paint scheme for the male T-rex on a maquette and then executed the paint job on the full-size character with some help from Trevor Hensley. ... (Duncan, The Winston Effect)

So, there's the story of the origin to our beloved big, mean, green machine that shredded up a Mercedes and stomped all over San Diego. BUT, I think there's a piece missing to this story, a piece that's hinted at between both stories. Both state that Shane Mahan came up with 8 head designs, and The Winston Effect adds a vital clue where it states that the final approved concept was transferred to 3D. I think that it's quite possible that more than just the approved concept made it to the sculpting table, and that it's very well possible that all 8 had been sculpted in maquette form. I've compiled the 3 maquettes that I know of below listed by potential order of conception.

Maquette #1)-Description: A sort of beigish green color, no neck wattle, no scars, only has the pronounced brow ridge. Maquette was not approved by Spielberg.-Image(s):

Maquette #6)-Description: The color scheme is closer to the finalized maquette, yet the wattle is not fully there. The striping pattern is also more broken. The right arm, also may have been broken as indicated by the odd posture. -Image(s): Partially painted image:

Spoiler:

Bronzed #6 Macquette)-Description: Retooled from the original #6 maquette by Jim Charmatz, the sculpt was changed to an even more dynamic pose from the original, opening the mouth more, and altering the feet a bit. One individual that came from a collector in China had a friend repaint the bronze into more lifelike colors, as seen below in the images section. This particular maquette currently resides in the collection of forum member Jerassic. -Image(s): Painted Copy-

Spoiler:

Images of the original bronze version-

Spoiler:

The bronze maquette currently resides in the collection of Mr. John Lanzendorf, a renowned dinosaur art collector living in Chicago, Illinois-

Spoiler:

Maquette #7)-Description: This one is the closest to the final approved maquette. It features all the details of the final maquette with slight differences. The neck wattle is slightly smaller than that of the final maquette, and the colors are slightly more vibrant. This maquette is most easily differentiated from the final by the arms, the left of which having a different posing. This maquette was not approved by Spielberg. -Images(s):

Spoiler:

Maquette #8)-Description: This was the finalized maquette, using a distinctive stone base. The neck wattle on this model is the largest, and being that this was the chosen maquette, it's possible to speculate that Spielberg had been interested in seeing a T. rex with a large wattle under it's neck. This maquette was used on set as well as by ILM, who scanned the model into the computer in order to create the CGI representation of the animal. This maquette was approved by Spielberg and is the closest visual we have of the TLW Buck other than the animatronic pre-repaint for JP///. This maquette is in fact theTLW Male T. rex. In props terms, this would be referred to as the "hero" maquette; the primary maquette used for production purposes, including being recasted for JP///. This maquette was further used in promotional and merchandising material for TLW, JP///, and beyond.-Image(s):

Spoiler:

Production images:

Promotional/Merchandising images:

And even the likeness repainted as the TLW Pinball backboard:

The problem, however, is that this leaves us with possibly five unaccounted for maquettes for the male alone, not counting the female maquette for TLW and the bronze recast(s-?) of maquette 2, 3, 4, or 5. I say possibly, because I discussed this with someone who talked to one of the SWS sculptors who worked on them, and he remembers there only be 2.